PAR sunlight exposure indicator for optimal plant placement

ABSTRACT

A sunlight exposure indicator device is disclosed that can determine the amount of time (e.g., hours) of PAR sunlight that occurs in a specific area for the optimal growth of a plant, as corresponds to the plant industry common designations of Full Shade, Partial Shade, Partial Sun and Full Sun. These designations can be used to determine plant selection for all types of plants including grasses, shrubs, flowers, vegetables and herbs, and trees. This device utilizes irreversible, slow-reacting, photochromic pigments applied to a substrate. Using multiple instances of this device will allow someone to easily test and accurately determine the amount of PAR sunlight (hours) received during a one-day sunlight cycle in multiple spots simultaneously. The sunlight exposure indicator device is a one-time-use, non-electronic, disposable device.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/890,226, filed Aug. 22, 2019, the entirety of which is incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates to detection of visible sunlightexposure, specifically photosynthetically active radiation (PAR),detection and irreversible photochromic pigments.

BACKGROUND

Different species and varieties of plants have many differentrequirements for optimal growth. One important requirement is the numberof hours and intensity of photosynthetically active radiation (PAR)sunlight exposure the plant receives during a one-day period. Plants usethe full spectrum of visible light, the spectrum range from 400-700 nm,in order for photosynthesis to occur and for the plant to grow, flower,reproduce and survive. This spectrum range is known asPhotosynthetically Active Radiation (PAR). Plants exposed toinsufficient or excessive PAR sunlight can fail to thrive, to developstrong roots, to leaf-out or to grow larger; become susceptible todisease; produce less flowers or fruit; or even die. Thus, it isimportant to know the amount of PAR sunlight a particular landscape areaexperiences before selecting and installing plants in those areas.However, it can be difficult to determine how many hours and theintensity of PAR sunlight a particular spot in a landscape areaexperiences during a one-day time period, due to various factors such asthe direction of the sun in relation to the area, whether there areobstructing buildings, trees or other shrubs that block sunlight atcertain times of the day, whether the area gets full sun in the morninghours or the more intense later afternoon hours, and the time of year.Attempting to estimate the number of hours of PAR sunlight exposure acertain area may experience by observing the outside area multiple timesper day is time-consuming and not very reliable. Residential gardenersas well as professional landscapers and commercial nurseries, who oftenguarantee their plants, lose time and money on lost plants if their ownor their customer's estimation of sunlight is incorrect and they installplants in an area not suitable to the plant's requirements.

SUMMARY OF THE INVENTION

Briefly, a PAR sunlight exposure indicator device is disclosed hereinthat can determine the amount of time (e.g., hours) and possiblyintensity of PAR sunlight that occurs in a specific area for the optimalgrowth of a plant, as corresponds to the plant industry's commondesignations of Full Shade, Partial Shade, Partial Sun and Full Suncategorized by a range of hours of sunlight needed per plant. The devicecould be designed to address a variation of the plant industry's commondesignations, using three categories instead of four: Full Shade,Partial Shade/Partial Sun, and Full Sun. These designations can be usedto determine plant selection for all types of plants including grasses,shrubs, flowers, vegetables and herbs, and trees.

In one embodiment, this device may utilize an irreversible,slow-reacting, photochromic pigment applied to a substrate that reactsby displaying different colors over a twelve and more (12+) hour periodbased on accumulated hours and possibly intensity of PAR sunlightexposure.

Many photoreactive products on the market are designed to react to UVlight primarily in the 260-390 nm range. A device that measures the UVspectrum would not give accurate results for the goal of optimal plantgrowth. By contrast, the device presented herein does not react to ormeasure UV sunlight. Rather, it only reacts to and measures the visiblespectrum of wavelengths known as PAR (400-700 nm) since this spectrum ofwavelengths is required for photosynthesis and optimal growth of plants.This device is unique from photochromic products that measure UV, forexample, sun protective products for human skin, UV ray damagemeasurement products, sterilization indicators, or merely fast colorchange products.

The irreversibility reactive aspect of the device presented herein isimportant to its function. The color changes that occur on the device donot revert back to its original color or fade at all during times ofshade or after the sun goes down. The irreversibility also makes thisdevice simple to use. A user can put this device in the landscape in theearly morning, leave it there all day, and retrieve it after the sungoes down and have permanent and accurate results.

The slow-reaction capabilities of the photochromic pigment(s) in thisdevice is also important for accurately measuring reaction times overthe course of 12+ hours, as opposed to the seconds or minutes ofreaction time of most (e.g., UV) photoreactive devices.

Because this device is simple and inexpensive to make, multiple devicesmay be packaged and sold together, allowing a user to easily testmultiple areas in a landscape simultaneously to accurately determine theamount of PAR sunlight (hours) received in each spot during one-day. Thesunlight exposure indicator device will be a one-time-use,non-electronic, disposable device.

Thus, in one form, a PAR sunlight exposure indicator device is providedthat comprises a stake member having a first section and a secondsection that is transverse to the first section; a sunlight-reactiveplanar member having a hole therein configured to accept the firstsection of the stake, wherein the sunlight-reactive planar membercomprises a substrate coated or impregnated with a layer of at least onetype of an irreversible photochromic pigment that is reactive toexposure to photosynthetically active radiation (PAR) and changes todifferent colors or shades of a color over different ranges ofcumulative hours of exposure to PAR; and a sticker configured to fit ontop of the sunlight-reactive planar member over the hole and over thesecond section of the stake to secure the sunlight-reactive planarmember to the stake.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the PAR sunlight exposure indicatordevice, according to an example embodiment.

FIG. 2A is a cross-sectional view of a sunlight-reactive planar memberthat employs a single irreversible, slow-reacting, photochromic pigmentfor detecting and displaying PAR sunlight exposure, according to a firstexample embodiment.

FIG. 2B is a top view of the sunlight-reactive planar member of FIG. 2Asubjected to 0.10 to 2 hours of PAR sunlight exposure (Full Shade).

FIG. 2C is a top view of the sunlight-reactive planar member of FIG. 2Asubjected to 3 to 4 hours of PAR sunlight exposure (Partial Shade).

FIG. 2D is a top view of the sunlight-reactive planar member of FIG. 2Asubjected to 5 to 6 hours of PAR sunlight exposure (Partial Sun).

FIG. 2E is a top view of the sunlight-reactive planar member of FIG. 2Asubjected to 7 or more hours of PAR sunlight exposure (Full Sun)

FIG. 3A is a cross-sectional view of a sunlight-reactive planar memberthat employs a single irreversible, slow-reacting, photochromic pigmentand a PAR-screening solution, for detecting and displaying PAR sunlightexposure, according to a second example embodiment.

FIG. 3B is a top view of the sunlight-reactive planar member of FIG. 3Athat is subjected to 10 to 2 hours of PAR sunlight exposure (FullShade).

FIG. 3C is a top view of the sunlight-reactive planar member of FIG. 3Athat is subjected to 3 to 4 hours of PAR sunlight exposure (PartialShade).

FIG. 3D is a top view of the sunlight-reactive planar member of FIG. 3Athat is subjected to 5 to 6 hours of PAR sunlight exposure (PartialSun).

FIG. 3E is a top view top view of the sunlight-reactive planar member ofFIG. 3A that is subjected to 7 or more hours of PAR sunlight exposure(Full Sun).

FIG. 4A-1 is a cross-sectional view of a sunlight-reactive planar memberhaving several different types of irreversible, slow-reacting,photochromic pigments for detecting and displaying PAR sunlightexposure, according to a third embodiment.

FIG. 4A-2 is a cross-sectional view of sunlight-reactive planar memberhaving several different thickness layers of an irreversible,slow-reacting, photochromic pigment for detecting and displaying PARsunlight exposure, according to the third embodiment.

FIG. 4B is a top view of the sunlight-reactive planar member of FIGS.4A-1 or FIG. 4A-2 that is subjected to 0.10 to 2 hours of PAR sunlightexposure (Full Shade).

FIG. 4C is a top view of the sunlight-reactive planar member of FIGS.4A-1 or FIG. 4A-2 that is subjected to 3 to 4 hours of PAR sunlightexposure (Partial Shade).

FIG. 4D is a top view of the sunlight-reactive planar member of FIG.4A-1 or FIG. 4A-2 that is subjected to 5 to 6 hours of PAR sunlightexposure (Partial Sun).

FIG. 4E is a top view of the sunlight-reactive planar member of FIGS.4A-1 or FIG. 4A-2 that is subjected to 7 or more hours of PAR sunlightexposure (Full Sun).

FIGS. 5A-1 and 5A-2 are cross-sectional views of a sunlight-reactiveplanar member featuring a combination of two different types ofirreversible, slow-reacting, photochromic pigments with a PAR-screeningsolution, for detecting and displaying hours of PAR sunlight exposure,according to a fourth example embodiment.

FIG. 5B is a top view of the sunlight-reactive planar member of FIG. 5Athat is subjected to 0.10 to 2 hours of PAR sunlight exposure (FullShade).

FIG. 5C is a top view of the sunlight-reactive planar member of FIG. 5Athat is subjected to 3 to 4 hours of PAR sunlight exposure (PartialShade).

FIG. 5D is a top view of the sunlight-reactive planar member of FIG. 5Athat is subjected to 5 to 6 hours of PAR sunlight exposure (PartialSun).

FIG. 5E is a top view of the sunlight-reactive planar member of FIG. 5Athat is subjected to 7 or more hours of PAR sunlight exposure (FullSun).

FIG. 6 illustrates a stake for securing the sunlight-reactive planarmember in place and securing it into the ground, according to an exampleembodiment.

FIGS. 7A and 7B illustrate a rectangular and oval peel-off sticker tosecure sunlight reactive planar member to the stake shown in FIG. 6 ,according to an example embodiment.

FIG. 8 illustrates an example of an interpretation key for the PARsunlight exposure indicator device, according to an example embodiment.

DETAILED DESCRIPTION OF DRAWINGS

Referring first to FIG. 1 , a PAR sunlight exposure indicator device 100is shown that includes a stake 110 (shown in more detail in FIG. 6 )inserted through the center-hole 112 of the sunlight-reactive planarmember (shown in more detail in FIGS. 2A-5E) 120 and a peel-off sticker130 (shown in more detail in FIG. 7 ) applied on top to secure thesunlight-reactive planar member 120 to the stake 110. This device 100may be sold and distributed in sunlight-blocking packaging so that itreacts to PAR sunlight only when removed from the packaging and placedout into an area that receives PAR sunlight. When the sunlight exposureindicator device 100 is fully assembled, and the stake is inserted intoa particular spot in a garden or potential landscape area, the device100 will begin reacting to PAR sunlight exposure and over the course ofthe daylight hours of one day, will react, and thus, visibly indicatethe amount of hours and possibly the intensity of PAR sunlight thatoccurs in that specific spot in one day. Multiple devices 100 may besold together in one package at a low cost so that a user can determinethe hours and possibly intensity of PAR sunlight exposure in multiplespots/locations in their landscape area all in one day. Thesunlight-reactive planar member 120 is for one-time use and isdisposable.

The sunlight-reactive planar member 120 may use one or more types of anirreversible photochromic pigment with slow or delayed reaction-time to400-700 nm wavelengths to visibly display total cumulative hours of PARsunlight exposure on a substrate. FIGS. 2A through 5E illustrate fivedifferent possible embodiments/variations to utilize irreversible,slow-reacting, photochromic pigment technology to indicate accrued PARsunlight exposure during a one-day period.

The sunlight-reactive planar member 120 include a substrate that may bemade of a cover-stock paper, such as 80 or 100 LB, cut into anapproximately 5″×5″ square (or possibly larger if need) with a smallhole cut in the center. The hole 112 may be just large enough for thestake 110 to fit through. The cover-stock paper may be thick enough tostay level for the duration of one day when attached to the stake withthe peel-off sticker. The paper is evenly or variably coated orimpregnated with one or more types of an irreversible photochromicpigment and possible PAR-screening (solution) layers that cause thesunlight-reactive planar member 120 to turn to different colors orshades of one color depending on the number of PAR sunlight hours thepaper is exposed to over the course of one full day. These new colorswill not fade or revert back during times of shade or even after the sunexposure has stopped, enabling a user to retrieve the sunlight-reactiveplanar member 120 at the end of the day (e.g., after sundown) and seethe accurate, permanent results of their test. The sunlight-reactiveplanar member 120 may also be coated with a suitable material to bewater repellent so that it still works if it rains lightly or the paperis contacted by water from another source, such as a sprinkler.

The sunlight-reactive planar member 120 is also referred to hereinsimply as sunlight-reactive planar member 120.

Single Irreversible Photochromic Pigment—FIGS. 2A-2E

FIG. 2A shows an enlarged cross-sectional view of the sunlight-reactiveplanar member 120 that employs a single type of an irreversible,slow-reacting, photochromic pigment 122 applied evenly to a substrate124. This specially formulated pigment 122 first appears as one color(or white) prior to exposure to PAR sunlight and then slowly over thecourse of 12+ hours of PAR sunlight exposure changes evenly todifferent, distinct colors or different shades of one color depending onthe time duration of cumulative PAR sunlight exposure the paperexperiences. This pigment 122 is formulated to have delayed or slowphotochromic reactions to the PAR sunlight exposure enabling it to veryaccurately and visually indicate the number of PAR sunlight exposurehours (or fractions thereof) in that area. A description of a possiblemanufacturing process and a list of possible compounds to derive thephotochromic pigment are described in more detail below.

FIGS. 2B-2E show the sunlight-reactive planar member 120 after differenttime durations of accrued sunlight exposure for the embodiment shown inFIG. 2A. A key (shown in FIG. 8 ) will be provided that explains theresults in terms of the four, common plant industry categories of FullShade, Partial Shade, Partial Sun and Full Sun. For example, the papercould be shades of very light grey if more than zero and up to 2 hoursof PAR sunlight exposure occurs (FIG. 2B) and the key would indicatethat this shade of grey represents Full Shade. The paper could be shadesof medium grey if 3 to 4 hours of PAR sunlight exposure occur (FIG. 2C)and the key would indicate that this shade of grey represents PartialShade. The paper could be shades of deep grey if 5 to 6 hours of PARsunlight exposure occurs (FIG. 2D) and the key would indicate that thisshade of grey represents Partial Sun. Finally, the paper could be almostblack if 7 or more hours of PAR sunlight exposure occurs (FIG. 2E) andthe key would indicate that this color represents Full Sun.

Single Irreversible Photochromic Pigment with PAR Screening—FIGS. 3A-3E

FIG. 3A shows the cross-sectional view of the sunlight-reactive planarmember 120 with a single irreversible, slow-reacting, photochromicpigment 122 applied evenly to the substrate 124 and a PAR-screeningsolution or physical PAR-screening device (such as an optical filter)126 in increasing strength levels is applied in a graduated manner ontop of the pigment-coated/impregnated layer. This PAR-screening solutionwill affect the pigment's PAR sunlight reaction time. For example, noPAR-screening solution applied in a first strip (section) 126A of thepaper so in this first strip, the pigment-coated/impregnated paper willchange colors if it receives any amount of PAR sunlight. A second strip126B of the sunlight-reactive planar member 120 will have a minimalstrength PAR-screening solution applied to it. The screening solutionwill prevent that strip of the pigment-coated/impregnated paper fromchanging colors until after it has been exposed to PAR sunlight for 3 ormore hours, at which point this strip will appear a distinctivelydifferent color as indicated on the key. A third strip 126C of the paperwill have a medium strength PAR-screening solution applied to it. Thisscreening solution will prevent that third strip of thepigment-coated/impregnated paper from changing colors until after it hasbeen exposed to PAR sunlight for 5 or more hours, at which point thisstrip will appear a distinctively different color as indicated on thekey. A fourth strip 126D of the paper will have the strongest strengthPAR-screening solution applied to it. This screening solution willprevent the pigment-coated/impregnated paper from changing colors untilit has been exposed to PAR sunlight for 7 or more hours, at which pointthis strip will appear a distinctively different color as indicated onthe key. It should be understood different strengths of the strips126A-126D of the PAR screen layers may be achieved by differentthicknesses of the same type of PAR screen material or by differenttypes of PAR screen materials.

FIGS. 3B-3E illustrate the possible visible differences thesunlight-reactive paper may have depending on the amount of accrued PARsunlight exposure for the embodiment shown in FIG. 3A. For example, anarea that receives no more than 2 hours of sunlight exposure would onlyhave a visible color change in the first strip 126A of thesunlight-reactive paper (FIG. 3B); the rest of the paper would have nochange in color. This test result would be represented as Full Shade onthe key. An area that receives between 3 and 4 hours of PAR sunlightexposure but no more would have visible color changes in the first andsecond strips 126A and 126B on the sunlight-reactive paper (FIG. 3C);the remaining half of the paper would have no change in color. This testresult would be represented as Partial Shade on the key. An area thatreceives between 5 and 6 hours of PAR sunlight exposure but no morewould have visible color changes in the first, second and third strips126A, 126B and 126C of the sunlight-reactive paper (FIG. 3D); theremaining quarter of the paper would have no change in color. This testresult would be represented as Partial Sun on the key. An area thatreceives 7 or more hours of PAR sunlight exposure would have visiblecolor changes in all four strips 126A, 126B, 126C and 126D of the entiresunlight-reactive paper (FIG. 3E). This test result would be representedas Full Sun on the key.

Four Different Photochromic Pigments—FIGS. 4A-1, 4A-2, 4B-4E

FIG. 4A-1 shows a cross-sectional view of sunlight-reactive planarmember 120 with four different types of irreversible, photochromicpigments applied e.g., pigments 122A, 122B, 122C and 122D, a differentpigment for each strip of the paper. Each photochromic pigment isspecially formulated to have different sunlight reaction speeds. Eachpigment may have the same starting color or may have different startingcolors prior to sunlight exposure. A first pigment 122A applied on thefirst strip of the paper will have a moderately slow photochromicreaction time, resulting in a change of paper color if any PAR sunlightexposure occurs. A second pigment 122B applied only to the second stripof the paper will be formulated to have a slower photochromic reactiontime, resulting in a change of paper color in that strip only if 3 ormore hours of PAR sunlight exposure occurs. A third pigment 122C appliedonly to the third strip of the paper will be formulated to have an evenslower photochromic reaction time, resulting in a change of color inthat strip only if 5 or more hours of PAR sunlight exposure occur. Afourth pigment 122D applied only to the fourth strip of the paper willbe formulated to have the slowest photochromic reaction time, resultingin a change of color in that strip only if 7 or more hours of PARsunlight exposure occurs.

FIG. 4A-2 shows a variation the sunlight-reactive planar member 120 maybe coated in different sections or strips with different thicknesses (ordifferent impregnation densities) of the same type of irreversiblephotochromic pigment. For example, a first section or strip is coated orimpregnated with a first thickness of an irreversible photochromicpigment, as shown at 123A, a second section or strip is coated with asecond thickness, greater than the first thickness, (or a secondimpregnation density) of an irreversible photochromic pigment, as shownat 123B, a third section or strip is coated or impregnated with a thirdthickness (or a third impregnation density), greater than the secondthickness, of an irreversible photochromic pigment, as shown at 123C,and a fourth section or strip is coated or impregnated with a fourththickness (or a fourth impregnation density), greater than the thirdthickness, of an irreversible photochromic pigment, as shown at 123D.The different sections or strips 123A-123D may have different reactivetimes to PAR exposure. For example, the section or strip 123A with athinner coating/less dense impregnation of irreversible photochromicpigment may be more slowly reactive or more quickly reactive, dependingon the type of irreversible photochromic pigment than the sections orstrips 123B-123D with progressively thicker coatings (or more denseimpregnation) of irreversible photochromic pigment. That is, dependingon the type of irreversible photochromic pigment, the reactivity to PARexposure may be slower for a thinner layer or slower for a thickerlayer.

FIGS. 4B-4E are illustrations of the possible visible differences thesunlight-reactive paper may have depending on the amount of accrued PARsunlight exposure for the embodiments shown in FIGS. 4A-1 and 4A-2 . Forexample, an area receiving no more than 2 hours of sunlight exposure ina day would show color change in only a first strip (FIG. 4B) 127A; therest of the paper would have no change in color. This test result wouldbe represented as Full Shade on the key. An area receiving between 3 and4 hours of PAR sunlight exposure but no more would have visible colorchanges on first and second strips 127A and 127B of thesunlight-reactive paper (FIG. 4C); the remaining half would have nochanges. This test result would be represented as Partial Shade on thekey. An area receiving between 5 to 6 hours of PAR sunlight exposure butno more would have color changes on the first, second and third strips127A, 127B and 127C of the sunlight-reactive paper (FIG. 4D); theremaining quarter of the paper would have no change in color. This testresult would be represented as Partial Sun on the key. An area receiving7 or more hours of PAR sunlight exposure would have visible colorchanges on the entire sunlight-reactive paper, across all four strips127A, 127B, 127C and 127D (FIG. 4E). The test result would berepresented as Full Sun on the key.

Two Different Irreversible Photochromic Pigments with Screening—FIGS.5A-1, 5A-2, 5B-5E

FIGS. 5A-1 and 5A-2 shows the cross-sectional views of thesunlight-reactive planar member 120 with a combination of two differentirreversible, slow-reacting, photochromic pigments applied, in twopossible variations (denoted Variation 1 and Variation 2 in FIGS. 5A-1and 5A-2 ), to the paper and then a sun PAR-screening solution orphysical screening layer applied on top. This method uses two of thespecially formulated pigments as described above in connection withFIGS. 4A-4E, one pigment having a mildly slow photochromic reaction timeand the other pigment having a much slower photochromic reaction timeand then using screening methods, such as described above in connectionwith FIGS. 3A-3E, to further delay the photochromic reaction times ofthe two pigments in order to achieve the visible color changesassociated with Full Shade, Partial Shade, Partial Sun and Full Sun PARsunlight exposure times.

The first variation (Variation 1) shown in FIG. 5A-1 involves applyingthe two pigments 122A and 122C, alternatingly, on each strip of thepaper and then applying the screening 126 just on top of the third andfourth strips/sections of the paper. The second variation (Variation 2)shown in FIG. 5A-2 involves applying a pigment 122A over the first twostrips/sections of the paper with the screening solution 126 over thesecond strip and then applies a pigment 122C to the third and fourthstrips/sections with the screening 126 over the fourth strip.

FIGS. 5B-5E illustrate the possible visible differences thesunlight-reactive paper may have depending on the amount of accrued PARsunlight exposure for the embodiment shown in FIG. 5A. For example, anarea receiving no more than 2 hours of sunlight exposure in a day wouldonly have a visible color change in the first strip 128A of thesunlight-reactive paper (FIG. 5B); the rest of the sunlight-reactiveplanar member (strips 128B, 128C and 128D) would have no change incolor. The test result would be represented as Full Shade on the key. Anarea receiving between 3 and 4 hours of PAR sunlight exposure but nomore would have visible color changes in the first and second strips128A and 128B on the sunlight-reactive paper (FIG. 5C); the remaininghalf of the paper would have no change in color. The test result wouldbe represented as Partial Shade on the key. An area receiving between 5to 6 hours of PAR sunlight exposure but no more would have visible colorchanges in the first, second and third strips 128A, 128B and 128C,respectively, of the sunlight-reactive paper (FIG. 5D); the remainingquarter of the paper would have no change in color. This test resultwould be represented as Partial Sun on the key. An area receiving 7 ormore hours of PAR sunlight exposure would have visible color changes onthe entire sunlight-reactive paper (FIG. 5E), across strips 128A, 128B,128C and 128D. This test result would be represented as Full Sun on thekey.

FIG. 6 illustrates the stake 110 used for holding the sunlight-reactivepaper upright and securing it in a spot a few inches above the ground ina particular landscape area. The stake may be T-shaped and comprise afirst section 114 that may be any suitable length, such as approximately5″ long, and a second section 116 that is transverse/perpendicular tothe first section 114, and may be 1½″ wide across the top (¾″ from thecenter point). The stake 110 may be made of a light weight and low-costmaterial, such as a metal, plastic or composite material, sturdy enoughto stand erect in soil for 14+ hours while supporting a small piece ofpaper. In operation, the stake 110 is inserted through the center-hole112 in the sunlight-reactive planar member 120 (FIG. 1 ) so that thesecond section 116 is on top of the sunlight-reactive planar member 120.The sunlight-reactive planar member 120 is secured to the second section(the T-part) 116 of the stake 110 with the peel-off sticker 130. Thefirst section 114 of the stake 110 has enough length to push down intothe soil and secure the device 100 in place while still holding thesunlight-reactive planar member 120 approximately 2-3″ above the soil soas to be sufficiently exposed to sunlight and to not become damp fromthe soil.

FIGS. 7A and 7B illustrate the rectangular or oval, peel-off, one-sidedsticker 130. The sticker 130 serves as one example of a fastener thatserves to fasten the planar member 120 to the stake 110. The sticker 130may be approximately 1¾″ in diameter or width. FIG. 7A shows the sticker130 has a rectangular shape and FIG. 7B shows the sticker 130 has anoval shape, as examples. The sticker 130 may be sturdy enough to adherethe sunlight-reactive planar member 120 over the second section of thestake 110 for 14+ hours. After the stake 110 is inserted through thecenter-hole 112 of the sunlight-reactive planar member 120 with thesecond section (T-portion) 116 on top of the sunlight-reactive planarmember 120, the peel-off sticker 130 is placed directly on top of thesecond section 116 of the stake 110 and also onto the sunlight-reactiveplanar member 120 securing the sunlight-reactive planar member 120 tothe stake 110, essentially holding the sunlight-reactive planar member120 to the top of the stake 110. This will keep the sunlight-reactiveplanar member 120 in place and level while the stake 110 is installed inthe ground. The sticker 130 may or may not be coated or impregnated withany irreversible photochromic pigment.

FIG. 8 illustrates an example of the PAR sunlight interpretation key200. This PAR sunlight interpretation key 200, which will be printed ona piece of paper, will be used to interpret the measurement results fromthe sunlight-reactive planar member 120. This key 200 will contain achart of colors which match the colors that appear on thesunlight-reactive paper prior to and after exposure to PAR sunlight overincreasing hours. After placing the fully assembled PAR sunlightexposure indicator device in a particular landscape spot all day, thesunlight-reactive paper will display a certain color or colors. The userwill hold the exposed PAR sunlight-reactive paper up to theinterpretation key and match up the color results. Adjacent to eachcolor on the key will be a list of the total accrued number of hours ofPAR sunlight indicated by that color. The PAR sunlight interpretationkey 200 will then explain how the number of hours of sunlight exposurecorresponds with the plant industry common designations of Full Shade,Partial Shade, Partial Sun and Full Sun.

Full Shade—0 to 2 hours of PAR sunlight exposure either direct orfiltered

Partial Shade—3 to 4 hours of PAR sunlight exposure

Partial Sun—5 to 6 hours of PAR sunlight exposure

Full Sun—7 or more hours of PAR sunlight exposure

Note that this device may be configured to present a variation of thePAR exposure test results, such that it shows three categorydesignations of results (hours of accrued PAR exposure) per a variationon the plant industry common designations of Full Shade, PartialShade/Partial Sun, and Full Sun, as defined below:Full Shade—0 to 3 hours of PAR sunlight exposure either direct orfilteredPartial Shade/Partial Sun—3 to 7 hours of PAR sunlight exposureFull Sun—7 or more hours of PAR sunlight exposure

Manufacturing Process

The sunlight-reactive planar member 120 for the device 100 may beproduced by printing photochromic pigment(s) on a sheet of paper whichis then cut down into individual components, keeping the cost per unitlower. The precise amount and thickness of the irreversible,slow-reacting, photochromic pigment(s) to be applied to the paper may bedetermined through trial and error testing. The precise amount,thickness, and strength of the possible PAR-screening solution (used incertain embodiments described above) and the method for applying it ontop of the pigment may be determined through trial and error testing.The irreversible, slow-reacting, photochromic pigments may be derivedfrom or contain any suitable one or more types of photochromic dyeswhich, when implemented for use with the indicator device are capable ofperforming in a manner as described herein. Some examples ofirreversible photochromic dyes include, without limitation, diarylethenecompounds, Spiropyran compounds, azobenzene compounds, fulgidecompounds, and quinone compounds; as well as inorganic compounds such ascertain silver and zinc halides (e.g., silver chloride), or tungstenoxide or other oxide compounds; or coordination complexes such as sodiumnitroprusside and the ruthenium sulfoxide. The precise formulation maybe determined through trial and error testing. The possiblesun-screening solution may contain agents such as titanium dioxide,kaolin, talc, zinc oxide, iron oxide, calamine, ichthammol, calciumcarbonate, magnesium oxide, bemotrizinol, avobenzone, bisoctizole,benzophenone-3, ecamsule, and silatriazole. The precise formulation willbe determined through trial and error testing.

Applications of the Device

The sunlight indicator device 100 is useful for commercial andresidential users. Related commercial businesses such as nurseries,hardware stores, landscape companies or large scale yard and landscapeproduct distributers might sell or use this product. Plant nurseries,commercial retailers which sell plants and landscape installers oftenguarantee the plants they install or sell on good faith that theinstaller has accurately determined sunlight exposure. These companiescould suggest their customers use this sunlight exposure indicatordevice 100 in order to receive a full guarantee. Landscaping companiescould utilize these devices on a client site as an aid in selecting theplants for the client. Residential users could use this device innumerous locations on the property around their home to determine, forexample, where to locate a vegetable garden, what type of annual flowerswill do best near the front door, whether full shade shrubs areappropriate on the north side of the house, whether the north side ofthe house gets enough morning and afternoon sun to select partial shadeor even partial sun shrubs. Residential users or landscapers can alsouse this device to determine the best type of grass sod or seed to usein a yard. This device 100 could even be used inside a home forselecting the proper house plant for a particular spot in the home.These are just some of the examples of uses of this device.

In summary, in one form, an apparatus is provided comprising: a stakemember having a first section and a second section that is transverse tothe first section; a sunlight-reactive planar member having a holetherein configured to accept the first section of the stake, wherein thesunlight-reactive planar member comprises a substrate coated orimpregnated with a layer of at least one type of an irreversiblephotochromic pigment that is reactive to exposure to photosyntheticallyactive radiation (PAR) and changes to different colors or shades of acolor over different ranges of cumulative hours of exposure to PAR; anda sticker or other attachable securing device configured to fit on topof the sunlight-reactive planar member over the hole and over the secondsection of the stake to be secured on top of the sunlight-reactiveplanar member to the stake. The substrate of the sunlight-reactiveplanar member may be made of a paper material. The apparatus may fathercomprise a water repellent coating on the sunlight-reactive planarmember. In one form, the irreversible photochromic pigment is reactiveto PAR, the visible light spectrum of 400 nm-700 nm.

In one form, the layer of the irreversible photochromic pigment is asingle type of irreversible photochromic pigment. In this case,substrate comprises a plurality of sections of the to which acorresponding different strength PAR-screening layer is disposed overthe layer of the irreversible photochromic pigment such that theplurality of sections have different reactivity to different ranges ofcumulative hours of exposure to PAR. In a variation, the substratecomprises a plurality of sections to which a PAR-screening coating ofcorresponding different thicknesses is disposed over the layer ofirreversible photochromic pigment such that the plurality of sectionshave different reactivity to different ranges of cumulative hours ofexposure to PAR.

In another form, the substrate comprises a plurality of sections of thesubstrate to which an irreversible photochromic pigment of correspondingdifferent thicknesses is disposed or impregnated such that the pluralityof sections have different reactivity to different ranges of cumulativehours of exposure to PAR. The apparatus may comprise a PAR-screeninglayer disposed over one or more of the plurality of sections such thatthe plurality of sections have different reactivity to different rangesof cumulative hours of exposure to PAR.

In still another form, the substrate comprises a plurality of sectionsof the substrate which are coated with at least two correspondingdifferent types of irreversible photochromic pigments such that theplurality of sections have different reactivity to different ranges ofcumulative hours of exposure to PAR. In this case, the apparatus maycomprise a PAR-screening layer disposed over one or more of theplurality of sections such that the plurality of sections have differentreactivity to different ranges of cumulative hours of exposure to PAR.

In one form, the different ranges of cumulative hours of exposure to PARcorrespond to common plant industry categories of Full Shade, PartialShade, Partial Sun and Full Sun, or Full Shade, Partial Shade/PartialSun, and Full Sun.

In yet another form, an apparatus is provided comprising: a planarmember comprising a substrate coated or impregnated with a layer of atleast one type of an irreversible photochromic pigment that is reactiveto exposure to photosynthetically active radiation (PAR) and changes todifferent colors or shades of a color over different ranges ofcumulative hours of exposure to PAR; and a mounting device configured toaffix to the planar member and be inserted into the ground to hold theplanar member above a ground.

In still another form, an apparatus is provided comprising: a stakehaving a first section and a second section that is transverse to thefirst section; a sunlight-reactive planar member comprising a substratecoated or impregnated with a layer of at least one type of anirreversible photochromic pigment that is reactive to exposure tophotosynthetically active radiation (PAR) and changes to differentcolors or shades of a color over different ranges of cumulative hours ofexposure to PAR; and a fastener configured to secure the stake to thesunlight-reactive planar member.

The above description is intended by way of example only. Although thetechniques are illustrated and described herein as embodied in one ormore specific examples, it is nevertheless not intended to be limited tothe details shown, since various modifications and structural changesmay be made within the scope and range of equivalents of the claims.

What is claimed is:
 1. An apparatus comprising: a stake having a firstsection and a second section that is transverse to the first section; asunlight-reactive planar member having a hole therein configured toaccept the first section of the stake, wherein the sunlight-reactiveplanar member comprises a substrate coated or impregnated with a layerof at least one type of an irreversible photochromic pigment that isreactive to exposure to photosynthetically active radiation (PAR) andchanges to different colors or shades of a color over different rangesof cumulative hours of exposure to PAR; and a sticker configured to besecured on top of the sunlight-reactive planar member over the hole andover the second section of the stake to secure the sunlight-reactiveplanar member to the stake.
 2. The apparatus of claim 1, wherein thelayer of the irreversible photochromic pigment is a single type ofirreversible photochromic pigment.
 3. The apparatus of claim 2, andwherein the substrate comprises a plurality of sections to which acorresponding different strength PAR-screening layer is disposed overthe layer of the irreversible photochromic pigment such that theplurality of sections have different reactivity to different ranges ofcumulative hours of exposure to PAR.
 4. The apparatus of claim 2,wherein the substrate comprises a plurality of sections to which aPAR-screening coating of corresponding different thicknesses is disposedover the layer of irreversible photochromic pigment such that theplurality of sections have different reactivity to different ranges ofcumulative hours of exposure to PAR.
 5. The apparatus of claim 1,wherein the substrate comprises a plurality of sections to which anirreversible photochromic pigment of corresponding different thicknessesis disposed or impregnated such that the plurality of sections havedifferent reactivity to different ranges of cumulative hours of exposureto PAR.
 6. The apparatus of claim 5, and further comprising aPAR-screening layer disposed over one or more of the plurality ofsections such that the plurality of sections have different reactivityto different ranges of cumulative hours of exposure to PAR.
 7. Theapparatus of claim 1, wherein the substrate comprises a plurality ofsections to which are coated with at least two corresponding differenttypes of irreversible photochromic pigments such that the plurality ofsections have different reactivity to different ranges of cumulativehours of exposure to PAR.
 8. The apparatus of claim 7, and furthercomprising a PAR-screening layer disposed over one or more of theplurality of sections such that the plurality of sections have differentreactivity to different ranges of cumulative hours of exposure to PAR.9. The apparatus of claim 1, wherein the different ranges of cumulativehours of exposure to PAR correspond to common plant industry categoriesof Full Shade, Partial Shade, Partial Sun and Full Sun, or Full Shade,Partial Shade/Partial Sun, and Full Sun.
 10. The apparatus of claim 1,wherein the substrate of the sunlight-reactive planar member is made ofa paper material.
 11. The apparatus of claim 10, further comprising awater repellent coating on the sunlight-reactive planar member.
 12. Theapparatus of claim 1, wherein the irreversible photochromic pigment isreactive to PAR, the visible light spectrum of 400 nm-700 nm.
 13. Anapparatus comprising: a planar member comprising a substrate coated orimpregnated with a layer of at least one type of an irreversiblephotochromic pigment that is reactive to exposure to photosyntheticallyactive radiation (PAR) and changes to different colors or shades of acolor over different ranges of cumulative hours of exposure to PAR; anda mounting device configured to affix to the planar member and beinserted into a ground to hold the planar member above the ground. 14.The apparatus of claim 13, wherein the layer of the irreversiblephotochromic pigment is a single type of irreversible photochromicpigment.
 15. The apparatus of claim 13, wherein the substrate comprisesa plurality of sections to which a corresponding different strengthPAR-screening layer is disposed over the layer of the irreversiblephotochromic pigment such that the plurality of sections have differentreactivity to different ranges of cumulative hours of exposure to PAR.16. The apparatus of claim 13, wherein the substrate comprises aplurality of sections to which an irreversible photochromic pigment ofcorresponding different thicknesses is disposed or impregnated such thatthe plurality of sections have different reactivity to different rangesof cumulative hours of exposure to PAR.
 17. The apparatus of claim 13,wherein the different ranges of cumulative hours of exposure to PARcorrespond to common plant industry categories of Full Shade, PartialShade, Partial Sun and Full Sun, or Full Shade, Partial Shade/PartialSun, and Full Sun.
 18. An apparatus comprising: a stake having a firstsection and a second section that is transverse to the first section; asunlight-reactive planar member comprising a substrate coated orimpregnated with a layer of at least one type of an irreversiblephotochromic pigment that is reactive to exposure to photosyntheticallyactive radiation (PAR) and changes to different colors or shades of acolor over different ranges of cumulative hours of exposure to PAR; anda fastener configured to secure the stake to the sunlight-reactiveplanar member.
 19. The apparatus of claim 18, wherein the layer of theirreversible photochromic pigment is a single type of irreversiblephotochromic pigment, and wherein the substrate comprises a plurality ofsections to which a corresponding different strength PAR-screening layeris disposed over the layer of the irreversible photochromic pigment suchthat the plurality of sections have different reactivity to differentranges of cumulative hours of exposure to PAR.
 20. The apparatus ofclaim 18, wherein the substrate comprises a plurality of sections towhich an irreversible photochromic pigment of corresponding differentthicknesses is disposed or impregnated such that the plurality ofsections have different reactivity to different ranges of cumulativehours of exposure to PAR.